1. Field of the Invention
The present invention relates generally to a circuit board connecting device, and more particularly to an improvement in a circuit board connecting device which is used for putting a pair of separate circuit boards in mutual electrical connection.
2. Description of the Prior Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Various kinds of electric or electronic parts are built even in a relatively small-sized electronic apparatus such as a mobile phone or the like. A major part of those parts are dispersedly mounted on, for example, a pair of separate circuit boards to fulfill their respective functions. In the relatively small-sized electronic apparatus, having an eye to the pair of separate circuit boards on which the electric or electronic parts are mounted, it is likely that the separate circuit boards are required to be arranged so as to reduce a space occupied thereby when the separate circuit boards are electrically connected with each other in a limited inside space of the apparatus.
In general, when a plurality of circuit boards, such as solid circuit boards or flexible printed circuit boards, are electrically connected with one another, a plurality of electrical connectors are mounted respectively on the circuit boards and one of the electrical connectors is coupled with another electrical connector so as to connect one of the circuit boards electrically with another circuit board. In the case where two separate circuit boards are electrically connected with each other, first and second electrical connectors are mounted respectively on the separate circuit boards to be coupled with each other. Each of the first and second electrical connectors is provided with, for example, a housing made of insulating material to be fixed to the separate circuit board and a plurality of signal contacts held by the housing so as to be electrically connected respectively with a plurality of signal terminals provided on the separate circuit board. Then, when the housing of the first electrical connector mounted on one of the separate circuit boards is engaged with the housing of the second electrical connector mounted on the other of the separate circuit boards so that the first and second electrical connectors are coupled with each other, the signal contacts held by the housing of the first electrical connector are connected respectively with the signal contacts held by the housing of the second electrical connector and thereby the signal terminals provided on one of the separate circuit boards are electrically connected respectively with the signal terminals provided on the other of the separate circuit boards through the signal contacts of the first and second electrical connectors.
Under a situation in which two separate circuit boards are electrically connected with each other in such a manner as mentioned above, in particular each of the separate circuit boards is used for managing high-frequency signals, the first and second electrical connectors mounted respectively on the circuit boards to be coupled with each other are desired to be put in an electromagnetically shielded condition wherein undesirable output electromagnetic wave noises leaking out of each of the first and second electrical connectors and undesirable input electromagnetic wave noises reaching from the outside to each of the first and second electrical connectors are reduced as much as possible. Therefore, there have been previously proposed several electrical connectors used for connecting two circuit boards with each other and provided with electromagnetic shielding means for making the electromagnetically shielded condition, as disclosed in, for example, the Japanese patent application published before examination under publication number H10-172685 (hereinafter, referred to as published prior art document 1) and the Japanese patent application published before examination under publication number 2008-218095 (hereinafter, referred to as published prior art document 2).
An electrical connector disclosed in the published prior art document 1 comprises a housing (an insulator (1)) made of insulating material to have a coupling portion (1a) for coupling with a mate electrical connector and to be fixed to a circuit board (a board (7)) so that the electrical connector is mounted on the circuit board, a plurality of signal contacts (contacts (3)) arranged on the housing, each of which has a contacting portion (3a) for coming into contact with a signal contact of the mate electrical connector and a connecting end portion (3b) for connecting with a signal terminal on the circuit board, and a conductive shell (5) fastened to the circuit board so as to cover wholly the housing mounted on the circuit board and the connecting end portions (3b) of the signal contacts at the outside of the housing on the circuit board. The contacting portion (3a) of each of the signal contacts is put in the coupling portion (1a) formed on the housing and the connecting end portion (3b) of each of the signal contacts projects to the outside from the housing to be soldered to the signal terminal on the circuit board. The conductive shell (5) is connected with a grounding terminal on the circuit board.
The coupling portion (1a) formed on the housing is coupled with the mate electrical connector fixed to another circuit board other than the circuit board to which the housing is fixed, so that each of the contacting portions (3a) of the signal contacts put in the coupling portion (1a) comes into contact with the signal contact of the mate electrical connector and the circuit board to which the housing is fixed and the circuit board on which the mate electrical connector is fixed are connected with each other. Under such a condition, the conductive shell (5) which is provided for covering wholly the housing mounted on the circuit board and the connecting end portions (3b) of the signal contacts at the outside of the housing on the circuit board, functions as electromagnetic shielding means to the electrical connector mounted on the circuit board.
Then, an electrical connector (a receptacle connector (1)) disclosed in the published prior art document 2 comprises a housing (a receptacle housing (3)) provided with a coupling portion (a receptacle coupling portion (32)) for coupling with a mate coupling portion (a plug coupling portion (142)) of a mate electrical connector (a plug connector (12)) and fixed to a circuit board (a first printed circuit board (21)) so that the electrical connector is mounted on the circuit board, a plurality of contacts (receptacle contacts (5)) including a plurality of receptacle signal contacts (5S), each of which is provided with an end portion (5d) to be connected with a signal terminal (a signal pad (21a)) on the circuit board and operative to contact with a mate signal contact (a plug contact (16)) of the mate electrical connector, and a conductive shell (7) attached to a outer peripheral surface of the housing to have a shell body (71) surrounding the coupling portion of the housing. A portion of each of the receptacle signal contacts (5S) is put in the coupling portion of the housing and the end portion (5d) of the receptacle signal contacts (5S) projects to the outside from the housing to be soldered to the signal terminal on the circuit board. The conductive shell (7) is connected with a grounding pad (21b) on the circuit board.
The coupling portion formed on the housing is coupled with the mate coupling portion of the mate electrical connector fixed to another circuit board other than the circuit board to which the housing is fixed, so that the portion of each of the receptacle signal contacts (5S) put in the coupling portion comes into contact with the mate signal contact of the mate electrical connector and the circuit board to which the housing is fixed and the circuit board to which the mate electrical connector is fixed are connected with each other. Under such a condition, the conductive shell (7) attached to the outer peripheral surface of the housing functions as an electromagnetic shielding means to the electrical connector mounted on the circuit board.
In each of the previously proposed electrical connectors used for connecting a pair of circuit boards with each other as described above, there are the following defects or disadvantages.
In the case of the electrical connector disclosed in the published prior art document 1, the housing and the conductive shell functioning as the electromagnetic shielding means are separately provided to be discriminated parts. When the housing and the conductive shell are mounted on the circuit board, first the housing on which the contacts are arranged is put on the circuit board and the connecting end portions of the signal contacts projecting to the outside from the housing are soldered to the signal terminals of the circuit board so that the housing is fixed to the circuit board, and then the conductive shell is fastened to the housing so as to cover wholly the housing mounted on the circuit board and the connecting end portions of the signal contacts at the outside of the housing on the circuit board. Consequently, separate processes of working are required respectively to fix the housing with the signal contacts arranged thereon to the circuit board and to fasten the conductive shell covering the housing to the circuit board, so that a total process of working for mounting the electric connector on the circuit board becomes complicated and troublesome.
Further, in the case of the electrical connector disclosed in the published prior art document 2, the conductive shell functioning as the electromagnetic shielding means is provided to be attached to the outer peripheral surface of the housing to have the shell body surrounding the coupling portion of the housing so as to be unable to cover the end portions of the receptacle signal contacts projecting to the outside from the housing to be soldered to the signal terminals on the circuit board. Consequently, the end portions of the receptacle signal contacts soldered to the signal terminals on the circuit board are not put in the electromagnetically shielded condition brought about by the conductive shell so that undesirable output electromagnetic wave noises leaking out of the end portions of the receptacle signal contacts and undesirable input electromagnetic wave noises reaching from the outside to the end portions of the receptacle signal contacts cannot be reduced. That is, in the electrical connector having the receptacle signal contacts is not electromagnetically shielded enough.